How Spaceflight Alters the Eyes

IRA FLATOW: This is “Science Friday.” I’m Ira Flatow. Of the many challenges facing astronauts living in space– how do you get regular exercise, how do you drink coffee, and yes, of course, the favorite– how do you go to the bathroom– one of the more unexpected consequences of spaceflight may be trouble reading the fine print. Yeah, why does microgravity make you need a different prescription for your glasses?

Lauren Silverman of KERA News in Dallas is here to talk about that and how doctors are trying to solve the problem. Along with other selected short subjects in science this week. Welcome to “Science Friday”, Lauren.

LAUREN SILVERMAN: Excited to be here.

IRA FLATOW: We’re very happy to have you. Let’s talk about the problems the astronauts are having. This is something many astronauts have complained about, isn’t it? Having trouble reading in space?

LAUREN SILVERMAN: Yeah, it’s something that really has only been talked about more recently. Because it isn’t something that happens to astronauts who just do a quick trip. But for people who are out on the International Space Station for long periods of time, say for six months, for example, they tend to have this problem.

Their eyes are changing, physically. Their vision is changing. And it doesn’t happen to everyone. But most astronauts do notice that they become far-sighted.

It happened to an astronaut, Michael Barrett. He’s also a doctor. And while he was up there flying hundreds of miles above Earth in 2009, he noticed his vision was changing. He was struggling to read manuals and checklists, which you can imagine are pretty important when you’re up there on the ISS.

IRA FLATOW: Details, details.

LAUREN SILVERMAN: Details, details– so he’s going through manuals and checklists, and he’s spending a lot of time on the Russian segment as well. So he’s trying to read in Russian in small print in a pretty dark space. And his vision is changing.

So when he finally lands back on Earth and he touches solid ground, he asks for something sort of strange– a hot shower and a spinal tap.

IRA FLATOW: Let me back that ups for a second. What does a spinal tap– I’ll ask the question– have to do with reading Russian?

LAUREN SILVERMAN: Well, he wanted to find out whether the pressure around his brain had changed. And one way you can do that is by looking at the cerebral spinal fluid, hence getting the spinal tap. And that is the prevailing theory of why vision is changing.

The idea is this. If you have no gravity, the fluid from your lower part of your body can migrate up into the brain instead of staying down towards your feet like it might on Earth. And that increases the pressure and reshapes the eyeballs.

IRA FLATOW: Wow. Wow. And did he find that the pressure in his brain, did he get this spinal tap. Did he find that it actually had changed?

LAUREN SILVERMAN: Well, he did. But the problem is he didn’t have a reading from before he left. So it’s pretty hard to compare by just looking at what happened after.

So I talked with another researcher who’s here in Dallas, Dr. Benjamin Levine, and he’s been studying this pressure theory for years. And his newest publication shows that the pressure on the brain while people are in microgravity, zero gravity, it is higher than it is say when you or I are standing on Earth. But it’s only slightly higher. It’s not what they expected. So I think we have a clip of Dr. Levine explaining how he’s had to modify this theory and come up with a pretty crazy sounding solution to try out.

BENJAMIN LEVINE: So we now think that perhaps this mild but persistent pressure may be the thing that’s stimulating remodeling behind the eye and causing the visual impairment. So one way to induce a gravity-like gradient is to encase the lower part of the body in a structure that is called lower body negative pressure. It’s an old technique that’s been around for more than 50 years. But we’ve been working with Under Armour, the garment company, to come up with a soft, almost like a sleeping sack or a pair of trousers, that you can put on at night, hook up to a vacuum cleaner, suck the blood and the fluid into the feet and unload the heart and the brain while you’re sleeping.

IRA FLATOW: Wow. Did they actually build this thing?

LAUREN SILVERMAN: Well, they’re working on it. And they’ve started to test these out. Of course, they need to test them on the International Space Station in order to figure out whether this could really work. But I asked Mike Barrett, the astronaut who was also the doctor, and he said he’d be willing to pull on a pair and try them out.

IRA FLATOW: You know, in the early days of rocketry in the ’50s, they used to create pressure suits, because the blood would drain out of your head. They were talking about blood pressure in those days, right? They didn’t talk about spinal fluid. So this is an idea, but using a different technique to let you see better. What–

LAUREN SILVERMAN: Yeah.

IRA FLATOW: I’m sorry, go ahead.

LAUREN SILVERMAN: Oh, I was just going to say and it’s interesting though, because there are people who are on Earth who actually have problems related to pressure in their brain. So if this could work to lower the pressure, it could be something that people who have traumatic brain injury, where there’s also oftentimes an increase in brain pressure that’s problematic, that other people here could use as well.

IRA FLATOW: Now that’s interesting because they always talk about spinoffs from this space race, Tang and that stuff. And that we might actually have something medical here. That’s kind of interesting.

Let’s move on to another story about how deeply paralyzed people might be able to communicate beyond blinking their eyes, you’ve reported on that.

LAUREN SILVERMAN: Yeah, so if you’ve read the book or seen the movie “The Diving Bell and the Butterfly”, you might know how difficult it can be for someone who’s deeply paralyzed to communicate. Sometimes they can use eye muscles and that creates the chance for them to be able to blink and sort of spell things out that way. But it’s pretty hard to communicate if someone can’t even control blinking.

So researchers in Europe have been developing a method to do that. And this week they published a paper in the journal “PLOS Biology” showing that they’ve managed to communicate with several patients who are in a complete locked in state. And they did it with something that looks a little bit like a swimming cap, a high tech swimming cap. And it measures electrical waves from the brain and blood flow.

And the first thing they had to do was put on this swim cap on the patients and calibrate it. So they had to ask the patients yes or no questions. You know, is Paris the capital of France? What’s your name? Is your name Martha, whatever it might have been.

And figure out the correct answers, whether they were getting the correct answers. And they got them about 70% of the time, which is better than chance. So that was shocking.

And then they started to ask them more open ended questions, one of which was, are you happy? And the people then could respond and the people who they asked, who were only a few patients who have ALS, said yes. So you can imagine what that might have been like for family members who haven’t had any communication at all.

IRA FLATOW: That’s interesting. Because we hear stories about experiments where people have the sort of similar situation. They have pro electrodes on their heads, and they try to move a muscle in their arms, or a robotic muscle and learning how to succeed in doing, just thinking about something. And then it happens. Maybe this is sort of that same thing.

LAUREN SILVERMAN: Exactly. Yeah, trying to go beyond visible muscle movements to sort of what’s below the surface.

IRA FLATOW: Mm-hmm. Let’s move on to Pew Research Center has a new survey out, which suggests most parents around the country actually are in favor of vaccinating school age kids. If you listen to some news reports, you would never believe that.

LAUREN SILVERMAN: Yeah, and this study was interesting because it looked at more than 1,500 people across the US. So it looked at Americans in general and how they feel about the requirement for school-aged children to get vaccinated, specifically for the measles, mumps, and rubella vaccine, which is the one that’s often in the news. And the Pew Report shows that more than 80% of Americans do support a school-based vaccine requirement. But about 17% say parents should be able to decide not to vaccinate, even if that means creating health risks for others.

IRA FLATOW: Do they offer any alternative of what they would do, or they were not asked that question?

LAUREN SILVERMAN: They weren’t asked that. But if you look at the breakdown, what’s interesting is that older people, older Americans who don’t necessarily have children who are of the age 0 to four where they might need to be getting vaccinated are much more in support of a requirement than younger Americans.

IRA FLATOW: And well, because a lot of us old enough to remember the polio vaccine and iron lungs and things like that. So we know what the consequences of not getting vaccination could be.

LAUREN SILVERMAN: That could be. And they saw also that people who are more science literate, maybe people who listen to more “Science Friday” seem to see the benefits much more outweighing the risks of vaccines.

IRA FLATOW: I want to talk about your last story called, “Saffron in Vermont.” We’re not talking maple syrup here. They’re growing saffron in Vermont?

LAUREN SILVERMAN: Yes, it sounds very strange, which is why it caught my attention. The state may be trying to move beyond cheese and craft beer and maple syrup. So basically what’s happened is that saffron is extremely expensive. It’s a spice that’s worth more than gold. It costs up to about $5,000 per pound.

And right now most of saffron, most saffron, about 80% comes from Iran. But there is a team at the University of Vermont who’s developing a process for growing the spice in Vermont, and get this– in winter. So what they’re doing is planting saffron in Vermont’s greenhouses, which are high tunnels. They call them high tunnels there. And they’re unheated greenhouses that the farmers use for other crops, like tomatoes, most of the year.

But there are a few months when there are neither grains nor tomatoes that are up in those high tunnels. And during those few months, this Iranian post-doc tried planting saffron. And he got a phenomenal yield of the spice.

IRA FLATOW: Wow, because that really is expensive stuff. You’re right. Yeah. Hundreds of dollars. Wow.

LAUREN SILVERMAN: So they could make some maybe paella or something else that needs some saffron in there coming from Vermont. But they’ve got to convince people to pick the stigmas from the saffron, which is really delicate and time consuming process.

IRA FLATOW: Well, with a price like that, I’m sure they’ll get people to do that. And I’m waiting for that first– I want to see that crop of saffron in Vermont. Thank you, Lauren. It’s good to have you. We’ll have you back. Lauren Silverman, Health, Science and Technology reporter at KERA News in Dallas. Thanks.

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